Establishment of Baseline Reference Geochemical Values in Tropical Soils of Western Ghats: Assessment of Periyar Basin with Special Reference to Contaminant Geochemistry

Based on the detailed geochemical studies of 184 soil samples from Periyar River Basin (PRB), a tropical monsoon dominated river basin (5398 km²) in the southern western Ghats (WGs) of India, a baseline reference data is established. The soils are mildly acidic with sandy loam and silt loam facies in non-monsoon to sandy loam and sandy clay loam in monsoon. The mean metal concentrations follow the upper continental crust and world shale values. The Geoaccumulation index (Igeo) shows unpolluted to moderately polluted category, except for Cu, Zn, and Ba, while Enrichment Factor (EF) indicates no to minor enrichment for all elements. Contamination factor (Cf) indicates low to considerable contamination for V, Rb, Sr, Ni, and low to very high contamination for Cu, Zn, and Ba. Three significant components are extracted by Principal Component Analysis (PCA), explaining 78.09% and 74.10% of the total variance for monsoon and non-monsoon seasons. Ti, Al, Fe, Ca, Na, K, V, Cr, Ni, Sr, and Ba exhibited common source of origin while anthropogenic origin is identified for Zn and Cu. The study will provide valuable information into the pedological characteristics of WGs river basins.     

Antibiotic resistant pathogens versus human impacts: a study from three eco-regions of the Chennai coast, southern India

We assessed the occurrence of pollution indicators and antibiotic resistant bacterial isolates from water and sediment samples of three different eco-regions of the Chennai coast between March - May of 2010. Total of 960 bacterial strains belonging to four genera were isolated which show the highest frequencies of resistance to vancomycin (53.6%) and penicillin (52.6%) (except Enterococcus sp., which is highly resistant to erythromycin) and lowest frequencies of resistance to chloramphenicol (3.43%), ciprofloxacin (3.95%), gentamicin (4.68%), and tetracycline (6.97%). The E. coli, Vibrio sp., Salmonella sp. and Enterococcus sp. show high frequency of resistance to 2-5 antibacterials of 60.4%, 45.83%, 69.16% and 46.6%, respectively. High pollution indices (PI - 6.66-14.06) and antibiotic resistance indices (ARI - 0.29-0.343) indicate that the coastal environment is highly exposed to antibiotic sources that suggesting to avoid direct contact.     

Shake table testing of liquefaction mitigation efficiency on pile foundations in sand stabilised with colloidal silica

Natural Hazards - Pile foundations in sands are susceptible to damage during earthquake-induced liquefaction. In the last decade, colloidal silica treatment in sand has been considered a novel...     

Degradation of Phenol in Aqueous Solution by Fenton,Sono‐Fenton and Sono‐photo‐Fenton Methods

The present work focuses on the performance of Fenton, sono‐Fenton, and sono‐photo‐Fenton processes for the oxidation of phenol present in aqueous solution. The effects of H₂O₂ concentration, Fe²⁺ concentration, pH, and initial phenol concentration on the oxidation of phenol were studied. The optimum Fe²⁺ and H₂O₂ concentrations for the Fenton process were 45 and 800 mg/L, respectively. For the sono‐Fenton process, the optimum Fe²⁺ and H₂O₂ concentrations were 30 and 800 mg/L, respectively. The optimal conditions for the sono‐photo‐Fenton process were found to be 20 mg/L of Fe²⁺ and 700 mg/L of H₂O₂. The optimum pH was found to be 3 for the processes investigated in the present study. The analysis of results showed that the sono‐photo‐Fenton method reduced the Fe²⁺ concentration by 30–50% and the H₂O₂ concentration by 12.5%. It was found that the sono‐photo‐Fenton technique showed better performance than the Fenton and sono‐Fenton processes for the oxidation of phenol. A lumped kinetic model was used to predict the chemical oxygen demand reduction and the model was found to fit the data.     

The crucial role of ocean�Catmosphere coupling on the Indian monsoon anomalous response during dipole events

This paper examines an issue concerning the simulation of anomalously wet Indian summer monsoons like 1994 which co-occurred with strong positive Indian Ocean Dipole (IOD) conditions in the tropical Indian Ocean. Contrary to observations it has been noticed that standalone atmospheric general circulation models (AGCM) forced with observed SST boundary condition, consistently depicted a decrease of the summer monsoon rainfall during 1994 over the Indian region. Given the ocean?Catmosphere coupling during IOD events, we have examined whether the failure of standalone AGCM simulations in capturing wet Indian monsoons like 1994 can be remedied by including a simple form of coupling that allows the monsoon circulation to dynamically interact with the IOD anomalies. With this view, we have performed a suite of simulations by coupling an AGCM to a slab-ocean model with spatially varying mixed-layer-depth (MLD) specified from observations for the 1994 IOD; as well as four other cases (1983, 1997, 2006, 2007). The specification of spatially varying MLD from observations allows us to constrain the model to observed IOD conditions. It is seen that the inclusion of coupling significantly improves the large-scale circulation response by strengthening the monsoon cross-equatorial flow; leading to precipitation enhancement over the subcontinent and rainfall decrease over south-eastern tropical Indian Ocean??in a manner broadly consistent with observations. A plausible physical mechanism is suggested to explain the monsoonal response in the coupled frame-work. These results warrant the need for improved monsoon simulations with fully coupled models to be able to better capture the observed monsoon interannual variability.     

Optimization of aqueous methylparathion biodegradation by Fusarium sp in batch scale process using response surface methodology

Biotreatment of methylparathion (O,O-dimethyl-O-4-nitrophenyl phosphorothioate) was studied in aqueous mineral salts medium containing fungal culture to demonstrate the potential of the pure culture (monoculture) of Fusarium sp in degrading high concentration of methylparathion. A statistical Box–Behnken design of experiments was performed to evaluate the effects of individual operating variables and their interactions on the methylparathion removal with initial concentration of 1,000 mg/L as fixed input parameter. A full factorial Box–Behnken design of experiments was used to construct response surfaces with the removal, the extent of methylparathion biodegradation, removal of chemical oxygen demand and total organic carbon, and the specific growth rate as responses. The temperature (X ₁), pH (X ₂), reaction time (X ₃) and agitation (X ₄) were used as design variables. The result was shown that experimental data fitted with the polynomial model. Analysis of variance showed a high coefficient of determination value of 0.99. The maximum biodegradation of methylparathion in terms of the methylparathion removal (Y ₁), chemical oxygen demand removal (Y ₂) and total organic carbon removal (Y ₃) were found to be 92, 79.2 and 57.2 % respectively. The maximum growth in terms of dry biomass (Y ₄) was 150 mg/L. The maximum biodegradation corresponds to the combination of following factors of middle level of temperature (X ₁ = 30 °C), pH (X ₂ = 6.5), agitation (X ₄ = 120 rpm) and the highest level of reaction time (X ₃ = 144 h). The removal efficiency of methylparathion biodegradation was achieved 92 %. It was observed that optimum biotreatment of methylparathion can be successfully predicted by response surface methodology.     

Parameter estimation of SWAT and quantification of consequent confidence bands of model simulations

Soil and Water Assessment Tool (SWAT) is a river basin scale model widely used to study the impact of land management practices in large, complex watersheds. Even though model output uncertainties are generally recognized to affect watershed management decisions, those uncertainties are largely ignored in model applications. The uncertainties of SWAT simulations are quantified using various methods, but simultaneous attempt to calibrate a model so as to reduce the uncertainty are seldom done. This study aims to use an uncertainty reduction procedure that helps calibrate the SWAT model. The shuffled complex evolutionary metropolis algorithm for uncertainty analysis is employed for this purpose, and is demonstrated using the data from the St. Joseph River basin, USA. The values of the performance indices, the r² and the Nash–Sutcliffe efficiency (NSE) for the simulations during calibration period was found to be 0.81 (same for r² and NSE) and 0.79 for validation period indicating a good simulation by the model. The results also indicate that the algorithm helps reduce the uncertainty (percentage of coverage?=?62% and average width?=?19.2 m³/s), and also identifies the plausible range of parameters that simulate the processes with less uncertainty. The confidence bands of simulations are obtained that can be employed in making uncertainty-based decisions on watershed management practices.     

Analysis of the Tsunami of December 26, 2004, on the Kerala Coast of India—Part III: Inundation and Initial Withdrawal

During the Indian Ocean tsunami of December 26, 2004, specific observations were made by our survey team about the arrival times of several tsunami waves, their amplitudes, maximum extent of horizontal inundation on land and initial withdrawal of the ocean. Here the observations on the horizontal inundation and initial withdrawal are presented and briefly discussed.